Estimated Number of Major Atlantic Hurricanes and Vertical Windshear ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE CONTRIBUTORS WHEN USING THIS DATA!!!!! NAME OF DATA SET: Estimated Number of Major Atlantic Hurricanes and Vertical Windshear LAST UPDATE: 6/2007 (Original receipt by WDC Paleo) CONTRIBUTOR: Johan Nyberg, Geological Survey of Sweden IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2007-056 SUGGESTED DATA CITATION: Nyberg, J., et al. 2007. Estimated Number of Major Atlantic Hurricanes and Vertical Windshear. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2007-056. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Nyberg, J., B.A. Malmgren, A. Winter, M.R. Jury, K.H. Kilbourne and T.M. Quinn. 2007. Low Atlantic hurricane activity in the 1970s and 1980s compared to the past 270 years. Nature, Vol. 447, No. 7145, pp. 698-702, 7 June 2007, doi:10.1038/nature05895. ABSTRACT: Hurricane activity in the North Atlantic Ocean has increased significantly since 1995. This trend has been attributed to both anthropogenically induced climate change and natural variability, but the primary cause remains uncertain. Changes in the frequency and intensity of hurricanes in the past can provide insights into the factors that influence hurricane activity, but reliable observations of hurricane activity in the North Atlantic only cover the past few decades. Here we construct a record of the frequency of major Atlantic hurricanes over the past 270 years using proxy records of vertical wind shear and sea surface temperature (the main controls on the formation of major hurricanes in this region) from corals and a marine sediment core. The record indicates that the average frequency of major hurricanes decreased gradually from the 1760s until the early 1990s, reaching anomalously low values during the 1970s and 1980s. Furthermore, the phase of enhanced hurricane activity since 1995 is not unusual compared to other periods of high hurricane activity in the record and thus appears to represent a recovery to normal hurricane activity, rather than a direct response to increasing sea surface temperature. Comparison of the record with a reconstruction of vertical wind shear indicates that variability in this parameter primarily controlled the frequency of major hurricanes in the Atlantic over the past 270 years, suggesting that changes in the magnitude of vertical wind shear will have a significant influence on future hurricane activity. GEOGRAPHIC REGION: Main Development Region of major hurricanes in the Atlantic Ocean, ~10–20°N, ~20-85° W PERIOD OF RECORD: 1730 - 1990 AD FUNDING SOURCES: Swedish Research Council grants to J.N. DESCRIPTION: This file contains estimated number of major hurricanes and vertical windshear (five-year running averages). Back propagation artificial neural networks were used to estimate past number of major hurricanes and vertical windshear. The relationships between combined input (independent) proxy records and the two output (dependent) instrumental records of number of major hurricanes and vertical windshear were determined unconnectedly. DATA: Estimated number of major hurricanes, five-year running averages Year 1990 1.76 1989 1.81 1988 1.63 1987 1.59 1986 1.48 1985 1.22 1984 1.33 1983 1.73 1982 1.76 1981 1.79 1980 1.90 1979 1.77 1978 1.73 1977 1.49 1976 1.65 1975 1.65 1974 1.63 1973 1.48 1972 1.57 1971 1.46 1970 1.43 1969 1.53 1968 1.89 1967 1.67 1966 2.15 1965 2.53 1964 2.43 1963 2.49 1962 2.96 1961 2.86 1960 2.95 1959 2.91 1958 2.79 1957 2.75 1956 2.73 1955 2.80 1954 2.94 1953 3.06 1951 3.44 1950 3.35 1948 3.47 1947 3.09 1946 3.16 1945 3.30 1944 3.18 1943 3.14 1942 2.96 1941 2.79 1940 2.60 1939 2.57 1938 2.54 1937 2.79 1936 3.04 1935 3.38 1934 3.61 1933 3.76 1932 3.74 1931 3.77 1930 3.78 1929 4.01 1928 4.07 1927 3.75 1926 3.65 1925 3.55 1924 3.26 1923 2.79 1922 2.81 1920 2.60 1919 2.42 1917 3.05 1916 3.19 1915 3.24 1914 3.46 1913 3.68 1911 3.69 1910 3.83 1909 4.03 1908 3.91 1907 3.77 1906 3.75 1905 3.75 1904 3.75 1903 3.74 1902 3.80 1901 3.77 1899 3.65 1898 3.49 1897 3.18 1896 2.98 1895 2.93 1894 3.04 1892 3.40 1891 3.71 1890 3.96 1889 4.11 1888 4.41 1887 4.35 1886 4.10 1885 3.85 1884 3.79 1883 3.82 1880 3.82 1879 3.93 1878 3.92 1877 3.87 1876 3.89 1875 3.95 1874 3.79 1873 3.69 1872 3.68 1871 3.70 1870 3.70 1869 3.69 1868 3.32 1867 2.73 1866 3.05 1865 2.45 1864 2.50 1863 2.60 1862 2.41 1861 2.29 1860 2.29 1859 2.34 1858 2.37 1857 2.43 1856 2.69 1855 2.53 1854 2.61 1853 2.73 1852 3.05 1851 3.43 1850 3.72 1849 3.84 1848 3.91 1847 3.96 1846 3.81 1845 3.71 1844 3.47 1843 3.45 1842 3.41 1841 3.51 1840 3.54 1839 3.63 1838 3.57 1837 3.39 1836 3.41 1835 3.26 1834 3.14 1833 3.07 1832 2.96 1831 2.65 1830 2.54 1829 2.25 1828 2.50 1827 3.04 1826 2.92 1825 2.96 1824 2.90 1823 3.08 1822 2.92 1821 2.67 1820 2.69 1819 2.85 1818 2.95 1817 3.07 1816 3.60 1814 3.78 1813 3.73 1812 4.07 1811 4.53 1810 4.99 1809 4.94 1808 4.88 1807 4.51 1806 4.19 1805 4.01 1804 3.98 1803 4.09 1802 4.04 1801 3.90 1800 3.73 1799 3.38 1798 2.69 1797 2.22 1795 1.84 1794 2.11 1793 3.38 1792 3.71 1791 3.75 1790 3.74 1789 3.67 1788 3.76 1787 3.80 1786 3.94 1785 4.02 1783 4.29 1782 4.27 1781 4.13 1780 3.95 1779 3.71 1778 3.62 1777 3.73 1776 3.84 1775 3.98 1773 4.51 1772 4.60 1771 4.59 1770 4.28 1769 4.02 1768 3.90 1767 3.94 1765 4.47 1764 4.75 1763 4.55 1762 4.32 1761 4.01 1760 3.86 1758 3.97 1757 4.04 1756 4.02 1755 3.69 1754 3.56 1753 3.50 1751 3.54 1750 3.61 1749 3.67 1748 3.54 1747 3.63 1745 3.68 1744 3.83 1743 3.78 1742 3.86 1741 3.77 1739 3.68 1738 3.21 1737 2.97 1736 2.68 1735 2.64 1733 2.78 1732 2.58 1731 2.42 1730 2.20 Estimated vertical windshear (Aug-Oct) five-year running averages (m/s) 1990 9.87 1989 10.57 1988 10.81 1987 11.30 1986 11.92 1985 12.60 1984 12.68 1983 11.88 1982 11.81 1981 11.61 1980 11.45 1979 11.69 1978 11.74 1977 11.70 1976 11.55 1975 11.68 1974 11.85 1973 12.04 1972 11.56 1971 11.11 1970 10.92 1969 10.32 1968 9.84 1967 10.19 1966 9.91 1965 9.58 1964 9.77 1963 9.67 1962 9.18 1961 9.34 1960 9.35 1959 9.30 1958 9.35 1957 9.34 1956 9.26 1955 8.78 1954 8.36 1953 8.42 1951 8.14 1950 8.57 1948 9.19 1947 9.55 1946 9.23 1945 8.48 1944 7.97 1943 7.57 1942 7.55 1941 7.74 1940 8.35 1939 8.68 1938 8.93 1937 8.43 1936 7.85 1935 7.09 1934 6.66 1933 6.44 1932 6.42 1931 6.38 1930 6.49 1929 6.29 1928 6.39 1927 6.85 1926 7.48 1925 8.19 1924 8.90 1923 8.90 1922 8.78 1920 9.24 1919 9.69 1917 9.66 1916 9.10 1915 8.71 1914 7.82 1913 6.98 1911 6.40 1910 6.29 1909 5.95 1908 6.27 1907 7.01 1906 7.57 1905 7.96 1904 7.96 1903 7.77 1902 7.16 1901 6.79 1899 6.82 1898 6.87 1897 7.20 1896 7.40 1895 7.40 1894 7.34 1892 6.78 1891 6.45 1890 6.22 1889 6.15 1888 5.93 1887 6.25 1886 6.62 1885 7.17 1884 7.33 1883 7.76 1880 8.02 1879 7.76 1878 7.65 1877 7.87 1876 7.71 1875 7.22 1874 7.64 1873 7.62 1872 7.48 1871 7.98 1870 8.25 1869 8.48 1868 8.85 1867 9.30 1866 9.11 1865 9.49 1864 9.52 1863 9.56 1862 9.76 1861 9.92 1860 10.00 1859 9.82 1858 9.70 1857 9.56 1856 9.25 1855 9.33 1854 9.33 1853 9.09 1852 8.84 1851 8.46 1850 7.91 1849 7.25 1848 6.85 1847 6.51 1846 6.79 1845 6.73 1844 7.09 1843 7.12 1842 7.18 1841 6.98 1840 6.93 1839 7.20 1838 7.72 1837 8.20 1836 8.67 1835 9.22 1834 9.36 1833 9.65 1832 9.87 1831 10.15 1830 10.18 1829 10.26 1828 10.14 1827 9.75 1826 9.62 1825 9.46 1824 8.95 1823 8.70 1822 8.65 1821 8.57 1820 8.27 1819 7.92 1818 7.46 1817 7.63 1816 7.38 1814 7.30 1813 7.30 1812 6.61 1811 6.00 1810 5.72 1809 5.69 1808 5.94 1807 6.37 1806 6.83 1805 7.14 1804 7.26 1803 6.98 1802 7.07 1801 7.38 1800 7.82 1799 8.41 1798 9.25 1797 9.68 1795 10.46 1794 9.81 1793 8.98 1792 8.55 1791 8.22 1790 7.78 1789 7.74 1788 7.54 1787 7.33 1786 7.20 1785 6.87 1783 6.52 1782 6.55 1781 6.44 1780 6.74 1779 7.50 1778 7.55 1777 7.33 1776 7.35 1775 6.84 1773 6.33 1772 6.33 1771 6.35 1770 6.83 1769 7.27 1768 7.44 1767 7.30 1765 6.04 1764 5.55 1763 5.56 1762 5.92 1761 6.46 1760 6.87 1758 6.99 1757 6.93 1756 6.98 1755 7.76 1754 8.00 1753 7.84 1751 8.20 1750 8.06 1749 7.93 1748 7.98 1747 7.59 1745 7.31 1744 7.13 1743 7.19 1742 7.11 1741 7.11 1739 7.32 1738 8.04 1737 8.64 1736 9.03 1735 9.05 1733 8.50 1732 8.56 1731 8.79 1730 9.13